function C=Covariance(X)
% Return covariance given data matrix X (row = object, column = feature)
% @author: Kardi Teknomo
% http://people.revoledu.com/kardi/index.html
[n,k]=size(X);
Xc=X-repmat(mean(X),n,1); % centered data
C=Xc'*Xc/n;               % covariance
